Wednesday, January 5, 2022

Repurposing the Damage Repair Protein Methyl Guanine Methyl Transferase as a Ligand Inducible Fusion Degron

Gosia M. Murawska, Caspar Vogel, Max Jan, Xinyan Lu, Matthias Schild, Mikolaj Slabicki, Charles Zou, Saule Zhanybekova, Manisha Manojkumar, Georg Petzold, Peter Kaiser, Nicolas Thomä, Benjamin Ebert, and Dennis Gillingham

ACS Chemical Biology 2021
DOI: 10.1021/acschembio.1c00771

We successfully repurpose the DNA repair protein methylguanine methyltransferase (MGMT) as an inducible degron for protein fusions. MGMT is a suicide protein that removes alkyl groups from the O6 position of guanine (O6G) and is thereafter quickly degraded by the ubiquitin proteasome pathway (UPP). Starting with MGMT pseudosubstrates (benzylguanine and lomeguatrib), we first demonstrate that these lead to potent MGMT depletion while affecting little else in the proteome. We then show that fusion proteins of MGMT undergo rapid UPP-dependent degradation in response to pseudosubstrates. Mechanistic studies confirm the involvement of the UPP, while revealing that at least two E3 ligase classes can degrade MGMT depending on cell-line and expression type (native or ectopic). We also demonstrate the technique’s versatility with two clinically relevant examples: degradation of KRASG12C and a chimeric antigen receptor.

Oncogenic KRAS G12C: Kinetic and Redox Characterization of Covalent Inhibition

Minh V. Huynh, Derek Parsonage, Tom E. Forshaw, Venkat R. Chirasani, G. Aaron Hobbs, Hanzhi Wu, Jingyun Lee, Cristina M. Furdui, Leslie B. P...